In the prior art, measuring instruments, such as combination squares and levels, are typically manufactured in a costly manner. For example, the frames for such measuring instruments are presently die cast in one piece so that the components, such as vials, which must be assembled with respect thereto must be done so in a costly manner. For example, U.S. Pat. No. 3,311,990 discloses a method of assembling a level including a level vial. In this patent, the level is formed from a one-piece member having a cross-section in the shape of an I-beam. Openings are formed in the web of the I-beam for receiving the level vial, and within the border of the openings notches are formed by a broaching technique to position the vial relative to the opening. The notches must be formed with relatively close tolerances and, therefore, require rather precise machining operations in order to produce the close fit required between the level frame and the vial. Accordingly, it would be desirable if such a measuring instrument could be constructed and assembled without the need for such costly precision machining operations. Moreover, in U.S. Pat. No. 3,311,990, the precision machined notches only position and locate the vial relative to the level frame, but do not hold it in place. As disclosed in this patent, additional covering plates are required to cover the web on both sides to hold the level vial in its proper position. Accordingly, it would also be highly desirable to eliminate the need for separate retaining members for holding the vial in its proper position. Such a development would reduce the number of parts required and the attendant costs, as well as the additional labor involved in assembling these additional components.
Broadly, it is an object of the present invention to provide an approved method for constructing and assembling measuring instruments which overcomes one or more of the aforesaid problems. Specifically, it is within the contemplation of the present invention to provide an improved method for constructing and assembling measuring instruments wherein the number of parts required and the labor involved are greatly reduced to simplify and reduce the cost of manufacture.